The present application claims priority to Japanese Application No. P2000-120742 filed Apr. 21, 2000, which application is incorporated herein by reference to the extent permitted by law.
The present invention relates to a solid-state pickup element that is capable of picking up color images, and a method for producing the same.
A solid-state pickup element that is capable of picking up color images obtains the respective colors of signals by providing color filters on light receptive areas. Such a solid-state pickup element is constructed so that light receptive areas are formed at the central parts of respective pixels arrayed on the surface side of, for example, a substrate, and respective color filters B, G and R, which are colored, for example, B(Blue), G(Green) and R(Red), are arrayed and formed on these light receptive areas one after another. Also, a light condensing lens (a so-called on-chip lens) is provided on the respective color filters B, G and R, by which incident light is condensed on the light receptive plane of the light receptive areas, whereby light can be efficiently condensed.
In a solid-state pickup element that has thus been constructed, only the light condensed by the light condensing lens of the light of respective wavelength bands that has transmitted through the respective color filters B, G and R arrayed between the light condensing lens and the light receptive areas will reach the light receptive plane of the respective light receptive areas, wherein full-color pickup can be carried out.
However, since, in such a solid-state pickup element that has thus been constructed, only the light of specified wavelength bands is selected by the respective color filters and is received by the light receptive areas, the light other than one with the specified wavelength band corresponding to the light receptive areas is not utilized in the respective light receptive areas even if it is the light of other specified wavelength bands necessary to obtain a color image. Therefore, the light received by the element surface is not sufficiently utilized, and it cannot be said that improvement in the sensitivity has been sufficiently attained.
Also, in the production of a color solid-state pickup element using respective color filters, it is difficult to form color filters by which light of an optional wavelength band can be separated and transmitted. Therefore, it is difficult to obtain the sufficient reappearance of colors.
Therefore, it is an object of the present invention to provide a color solid-state pickup element that is capable of achieving improvement in the sensitivity by efficiently utilizing the light received by the element surface and has an excellent color reappearance property, and a method for producing the same.
In order to achieve the object, a solid-state pickup element according to the invention is featured in that, in a plurality of light receptive areas arrayed and formed on the surface side of a substrate, a light polarizing prism that polarizes light incident from the surface side of the abovementioned substrate, and distributes to irradiate spectral light of a specified wavelength band onto the abovementioned respective light receptive areas is provided on the abovementioned substrate.
In such a solid-state pickup element thus constructed, spectral light of a specified wavelength band, which is polarized by a light polarizing prism is distributed and irradiated onto respective light receptive areas. Therefore, all light, of a specified wavelength band necessary to carry out color pickup, of the light received by the light polarizing prism will be irradiated onto any one of the respective light receptive areas, wherein color pickup efficiently using the received light can be carried out.
The first light condensing lens that condenses spectral light of the abovementioned specified wavelength band, which is polarized by the corresponding light polarizing prism, onto the corresponding light receptive areas is provided between the abovementioned respective light receptive areas and the abovementioned light polarizing prism, wherein spectral light of respective specified wavelength bands, which is polarized by the light polarizing prism, can be efficiently condensed on the respective light receptive areas, and the efficiency of the utilization of the spectral light can be highly increased.
The second light condensing lens that condenses light incident into the surface side of the abovementioned substrate is provided on the abovementioned light polarizing prism, and an in-layer lens that makes light condensed by the second condensing lens into a parallel beam and makes the same incident into the corresponding light polarizing prism is provided between the second light condensing lens and the abovementioned light polarizing prism, wherein the light can be efficiently condensed on the surface side of the substrate, and is made incident into the light polarizing prism as a parallel beam, and the efficiency of the utilization of the received light at the surface side of the substrate can be highly increased.
Light polarized by the abovementioned light polarizing prism is distributed and irradiated to at least three light receptive areas, wherein full-color pickup efficiently using the received light can be carried out.
A method for producing a solid-state pickup element includes the step of forming a convex pattern made of a prism material on a substrate in which light receptive areas are arrayed and formed on the surface side thereof, and the step of forming a prism material layer by a biased CVD method, which covers the abovementioned convex pattern, and forming a light polarizing prism consisting of the abovementioned convex pattern and the abovementioned prism material layer.
By such a method for producing a solid-state pick element, since a prism material layer that covers a convex pattern on the substrate is formed by the bias CVD method, a prism material layer having an inclined surface with respect to the substrate can be formed. Therefore, the surface of the prism material layer inclined with respect to the substrate is made into an incident surface, wherein a light polarizing prism, in which the prism material layer and the bottom plane of the convex pattern are made into an irradiation plane, can be formed on the substrate.
As described above, according to the solid-state pickup element of the invention, since a light polarizing prism is provided on the substrate in which light receptive areas are arrayed, all light, of specified wavelength bands necessary to carry out color pickup, of the light received by the light polarizing prism will be able to be irradiated onto any one of the respective light receptive areas, and color pickup efficiently using the received light can be executed. As a result, it becomes possible to a color solid-state pickup apparatus which has excellent sensitivity. Furthermore, since the light polarizing prism is used, it is possible to receive spectral light of optical wavelength bands by the respective light receptive areas, and it is possible to improve the color reappearance property of solid-state pickup elements.
Also, according to the method for producing a solid-state pickup element of the invention, since a prism material layer that is made of a prism material and covers the convex patterns is formed by the bias CVD method, it becomes possible to easily form a light polarizing prism on a substrate. Therefore, the process for producing a color solid-state pickup element equipped a on-chip light polarizing prism can be simplified.